There are several types of automatic L-type packaging machines currently being marketed. In the most common types, the product fed into the machine, either at 90.degree. or in line, drops down in front of a pusher and is then indexed into the film and into the seal zone. However, since there are certain unstable products which cannot tolerate being dropped, a machine has recently been introduced which eliminates the requirement for a drop by utilizing a two-stage pusher. In this machine, the product is initially advanced into position by a conveyor, a short stroke pusher arm is advanced into position behind the product, and then the pusher and product are indexed into the film and seal zone. During the return stroke of the pusher, the arm is retracted so as not to interfere with the next waiting product. While this device is suitable for certain products, it has inherent limitations. Since the nature of this mechanism is such that the pusher arm must be completely advanced and retracted once each cycle, it is obvious that, in order to achieve any reasonable level of speed, the pusher arm must be restricted to a relatively short length, which means that the product is essentially being pushed from one corner only. For many products, this is an unstable condition which results in twisting of the product and faulty packaging or interruption of the operation of the apparatus.
In the prior art, L-sealers have had the sealing frames, or at least the upper frame, hinged at the side of the path of travel of a package, so that the frame rotates about an axis which is parallel to this path of travel. This requires the sealing frame to pivot through an undesirably large angle and limits the speed of operation of the sealer.
In addition, in the prior art, bag-forming plows are fixed dimensionally so that, if it is desired to form bags of different sizes, plows of different sizes must be mounted on the machine. This is obviously time consuming and expensive and permits only limited variations in the sizes of bags which can be formed.
The apparatus of the invention overcomes the above-noted problems in the prior art and provides an efficient machine for handling a product, forming a bag for the product, and forming an L-seal to close the bag.